CA2188781A1

CA2188781A1 - Multilayer nonwoven thermal insulating batts

Info

Publication number: CA2188781A1
Application number: CA002188781A
Authority: CA
Inventors: Carol E. Herzberg
Original assignee: Individual
Current assignee: 3M Co
Priority date: 1994-05-20
Filing date: 1995-04-07
Publication date: 1995-11-30
Also published as: CN1052047C; JPH10500740A; NO964924L; KR970703455A; US5620541A; NZ284294A; CN1148418A; AU691278B2; US5437909A; DK0760029T3; EP0760029A1; DE69505521D1; NO964924D0; BR9507738A; WO1995032328A1; DE69505521T2; KR100379671B1; AU2286895A; ES2122586T3; EP0760029B1

Abstract

A multilayer nonwoven thermal insulating batt is provided. The batt comprises multiple layers of webs, each web being a blend of 5 to 100 weight percent bonding staple fibers and 0 to 95 weight percent staple fill fibers, the bonding fibers bonded to other bonding fibers and fill fibers at the points of contact to enhance the structural stability of the layers of the batt. Also provided is a method of making the thermal insulating nonwoven multilayer batt comprising the steps of: (a) forming a web of bonding staple fibers and staple fill fibers; (b) subjecting the web to sufficient heat to cause bonding of the bonding staple fibers to other bonding staple fibers and staple fill fibers at points of contact within the web to stabilize the web; and (c) forming a batt of multiple layers of said webs.

Description

W095/32328 2 1 8 8 7 8 1 E~1/~ O~S1 MULTILAYER NONWOVEN TIIERMAL INSULATING BATTS
Field of the Invention , 5 The present invention relates to improved insulating and cushioning structures made from synthetic fibrous materials and more 1~,. Li~,u~ ly to thermal insulating materials having the insulating p, r~ and feel of down.
o Ba~ . . ' of the Invention A wide variety of natural and synthetic filling materials for thermal insulation -.rl ' , such as outerwear apparel, e.g. jackets, stocking caps, and gloves, sleeping bags and bedding articles, e.g., pillows, comforters, quilts, and bedspreads, are known.
Natural feather down has found wide acceptance for thermal insulation ~ r ' , primarily because of its ~ ' ,, weight efficiency, softness, and resiliency. Properly fluffed and contained within an article or garment, down isgenerally recognized as the insulation material of choice. However, down compacts and loses its insulating properties when it becomes wet and can exhibit a 20 rather unpleasant odor when exposed to moisture. Also a carefully controlled cleaning and drying process is required to restore the fluffiness and resultant thermal insulating properties to an article in which the down has compacted.
There have been numerous attempts to prepare synthetic fiber-based structures having the cl,.l, ~,.,Le, ;~Li.,~ and structure of down. Several attempts have ~5 been made to produce substitutes for down by converting the synthetic fibrousmaterials into insulating batts configured to have fibers that have specific orientations relative to the &ces of the batt followed by bonding of the fibers to stabilize the web to afford improved insulating properties.

W095132328 21 8878~ P~.l/o.,. .'O~SI

Such attempts include a pillow formed of an assemblage of generally co-planar fibers encased in a casing, where the fibers are s ~ "~, p.,.~ ul~
to the major axis of the elliptical cross-section of the pillow surfaces to provide a degree of resiliency and fluffability; a thermal insulating material which is a web of .
blended microfibers with crimped bulking fibers which are randomly and thoroughly intermixed and ;.,t~ with the microfibers to provide high thermal resistance per unit thickness and moderate weight; and a nonwoven thermal insulating batt of entangled staple fibers and bonding staple fibers which are substantially parallel to the faces of the web at the face portions of the web and o substantially ~ ,.ldi~,uL~ to the faces of the batt in the central portion of the batt with the bondin~ staple fibers bonded to the structural staple fibers and other bonding staple fibers at points of contact.
Other structures include a blend of ~0 to 90 weight percent of spun and drawn, crimped staple synthetic polymeric microfibers having a diameter of 3 to 12 microns and 5 to 20 weight percent of synthetic polymeric staple .,.~,~,. urlbe. b having a diameter of from more than 12 up to 50 microns which is described as comparing favorably to down in thermal insulating properties and a synthetic fiber thermal insulating material in the form of a cohesive fiber structure of an assemblage of from 70 to 95 weight percent of synthetic polyrneric microfibers having diameter of from 3 to 12 microns and from 5 to 30 weight percent of synthetic polymeric ~ ur~b."~ having a diameter of 12 to 50 microns where at least some of the fibers are bonded at their contact points, the bonding being such that the density of the resultant structure is within the range of 3 to 16 kg/m3, the thermal insulating properties of the bonded assemblage being equal to or not ~ , less than the thermal insulating properties of the unbonded In this assemblage the entire assemblage is bonded together to WO gs/32328 2 1 8 8 7 8 1 ~ ~ ' o ~
maintain support and strength to the fine fibers without suffering from the lower thermal capacity of the macroflber cnmrt~n~nf A still further structure suggested for providing a resilient, thermaDy 1- bonded non-woven fibrous batt includes having uniform CU~ a;Vll modulus in5 one plane which is more than the cu.,.~ a;vil modulus measured in a direction ,ukl~ to that plane and a ' ~ uniform density across its thickness.
The batt is prepared by forming a batt comprising at least 2û% by weight of crimped and/or crimpable conjugate fibers, i.e., ~- r ' bonding fibers, having or capable of developing a crimp frequency of less than I û crimps per lo extended cm, and a decitex in the range of 5 to 3û. The batt is thermally bonded by subjecting it to an upward fluid flow heated to a t~".."~.. d~UI t: in excess of the softening component of the conjugate fiber to effect inter-fiber bonding.
Brief Summarv Of The Invention The present invention provides a nonwoven thermal insulating batt having multiple layers of webs, each web comprising a blend of bonding staple fibers and staple f~ll fibers, the bonding fibers bonded to other bonding fibers and to said staple fill fibers at points of contact to enhance the structural stability of each of 20 the layers of the batt. The batt may contain staple fill fibers of two or more deniers. Preferably, the batt is post treated, such as by surface bonding, to stabilize the layered structure.
The present invention also provides a method of making a thermal insulating nonwoven multilayer batt comprising the steps of:
(a) forming a web of bonding staple fibers and staple fill fibers;
(b) subjecting said web to sufficient heat to cause bonding of the bonding staple fibers to other bonding staple fibers and staple fill fibers at points of contact to stabilize the web, and W095/32v28 2 1 8 878 1 ~ Sl --(c) forming a batt of multiple layers of said webs.
Preferably, the web is formed by carding and the layering is achieved by cross-lapping the carded web. Further, the method preferably comprises post treating the batt, such as by surface bonding, to stabilize the layered structure.
The nonwoven thermal insulating batt of the present invention has thermal insulating properties, palticularly thermal weight Pffi~ nri~c, about ,u~y~ to or exceeding those of down, but without the moisture sensitivity of down. The presence of the individual layers of the multilayer batt increases the ~
softness or hand ofthe batt in ~u j..,...l;.-~ with improved thermal insulating properties compared to batt c~ and cu..~Llu~.~iulla having single layer structures.
The mechanical properties of the batt of the present invention such as its density, resistance to ~UIIIylv~ c forces, loft as well as its thermal insulating, properties can be verified over a significant range by changing the fiber der~ier, 5 basis weight, structural to bonding fiber ratio, type of fibers, surface texture of the layer faces, and bonding conditions.
Brief Description of the Drawin~s FIG. I is a . c;y. ~ iull of the multilayer nonwoven thermal insulating zo batt of the present invention.
FIG. 2 is a cross-sectional view of a preferred - ,l .o.l -~ of the multilayer nonwoven thermal insulating batt of the present invention..
Detailed Descrintion of the ~nvention ~5 The present invention,. as shown in FIG. 1 is a nonwoven thermal insulating batt 10 comprised of layers II which contain staple fill fibers 12 and staple bonding fibers 13. The bonding fibers bond to other bonding fibers and fill .. _ . .... . . . .. _ . . ...... . .. . . . ... . ... . . . ... ... .. . . . .

WOss/32328 2~88781 r~ o~1SS

fibers at points of contact within each layer such that the layers maintain their integrity.
Staple fill fibers, usually single component in nature, which are useful in J- the present invention include, but are not limited to, polyethylene 1~
polyamide, wool, polyvinyl chloride, acrylic and polyolefin, e.g., po:y~,.u~;l~,.l.,.
Both crimped and uncrimped structural fibers are useful in preparing the batts of the present invention, although crimped fibers, preferably having I to 10 crimps/cm, more preferably having 3 to 5 crimps/cm, are preferred.
The length of the structural fibers suitable for use in the batts of the lo present invention is preferably from 15 mm to about 50 mm, more preferably from about 25 mrn to 50 mm, although structural fibers as long as 150 mrn can be used.
The diameter of the staple fill fibers may be varied over a broad range.
However, such variations alter the physical and thermal properties of the stabilized batt. Generally, finer denier fibers increase the thermal insulating properties of the batt, while larger denier fibers decrease the thermal insulating properties of the batt. Useful fiber deniers for the structural fibers preferably range from about 0.2 to 15 denier, more preferably from about 0.5 to 5 denier, most preferably 0.5 to 3 denier, with blends or mixtures of fiber deniers often times being employed to obtain desired thermal and mechanical properties as well as excellent hand of the stabilized batt. Finer denier staple fibers of up to about 4 denier provide improved thermal resistance, drape, softness and hand which show more: ' as the denier is reduced. Larger denier fibers of greater than about 4 denier provide the batt with greater strength, cushioning and resilience with greater . ~. of these properties with increasing fiber denier.
A varjety of bonding fibers are suitable for use in stabilizing the layers of the batts of the present invention, including amorphous, meltable fibers, adhesive coated fibers which may be ~ uu~ly coated, and 1,;~ ,l bonding wo ssl32328 2 1 8 8 7 8 1 fibers which have an adhesive component and a supporting component arranged in a cuw.h,..~ c side-by-side, concentric sheath-core, or elliptical sheath-core along the length of the fiber with the adhesive component forming at least a portion of the outer surface of the fiber. The adhesive component of the ,, bondable fibers is preferably thermally bonded. The adhesive component of thermally bonding fibers must be thermally activatable (i.e., meltable) at a ,. d~UlC below the melt t~ ,.dLUlt; of the staple fill fibers of the batt.
A range of bonding fiber sizes, e.g. from about 0.5 to 15 denier are useful in the present invention, but optimum thermal insulation properties are realized if 0 the bonding fibers are less than about four denier and preferably less than about two denier in size. As with the staple fill fibers, smaller denier bonding fibers increase the thermal insulating properties, while larger denier bonding fibers decrease the thermal insulating properties of the batt. As with the staple fill fibers, a blend of bonding fibers of two or more denier can also be used.
The length of the bonding fibers is preferably about I S mm to 75 mrn more preferably about 25 mm to 50 mm, although fibers as long as 150 mm are useful.
Preferably, the bonding fibers are crimped, having I to 10 crimps/cm, more preferably having 3 to 5 crimps/cm. Of course, adhesive powders and sprays can also be used to bond the staple fill fibers, although difficulties in obtaining even distribution throughout the web reduces their desirability.
One particularly useful bonding fiber for stabilizing the batts of the present invention is a crimped sheath-core bonding fiber having a core of crystalline polyethylene lcl c~ llal~l~ surrounded by a sheath of an adhesive polymer of an activated uo~,uly~ f.... The sheath is heat softenable at a tclll~ dLulc lower than 25 the core material. Such fibers, available from Hoechst Celanese Corporation, are particularly useful in preparin~ the batts of the present invention and are described in U.S. Patent No. 5,256,050 and U.S. Patent No. 4,950,541. Other sheath~core . . .. . ... .. . .... ... ... . . ... ... . .. _ . .. .. .... .. ... .. .... _ ..

2 1 8 8 7 8 1 r~ [ 1~5 1 adhesive fibers may be used to improve the properties of the present invention.
RCLII ~ d~ive examples include fibers having a higher modulus core to improve the resilience of the batt or fibers having sheaths with better solvent tolerance to improve dry cleanability of the batts.
The amounts of staple fill fiber and bonding staple fiber in the batts of the present invention can vary over a wide range. Generally, the amount of staple bonding fiber in the batt can range widely. Preferably, the batt contains 5 to 100 weight percent staple bonding fiber and 0 to 95 weight percent staple fill fiber, more preferably 10 to 80 weight percent staple bonding fiber and 20 to 90 weighto percent staple fill fibers, most preferably 20 to 50 weight percent staple bonding fiber and 50 to 80 weight percent staple fill fiber.
The nonwoven thermal insulating batts of the invention are capable of proving thermal weight efficiencies of preferably at least about 20 clo/kg/m2, more preferably at least 25 clo/k g/m2 most preferably at ieast about 30 clo/kg/m2 and radiation parameters of less than about 20 (W/mK)(kglm3)( 100), more preferably less than about 15 (WlmK)(kg/m3)(100), more preferably less than 10 (W/mK)(kg/m3)(100).
The nonwoven batts of the present invention preferably have a bulk density of less tham about 0.1 g/cm3, more preferably less than about 0. 005 g/cm3, mostpreferably less than about 0.003 g/cm3. Effective thermal insulating properties are achievable with bulk densities as low as 0.001 g /cm3 or less. To attain these buik densities, the batts preferably have a thickness in the range of about 0.5 to 15 cm, more preferably 2 to 20 cm, most preferably 5 to 15 cm, and preferably have a basis weight firom 20 to 600 g/m2, more preferably 80 to 400 g/m2, most preferably 100 to 300 g/m2.
The webs which comprise the layers of the batt of the invention can be prepared using any eul-~s~ iul~ai web forming process including carding, wo gsl3u28 2 1 8 8 7 8 1 P~ c~c ~ ~5 ~ ~

garnetting, air laying such as by Rando-WebberTM, etc. Carding is generally preferred Each layer is preferably about 1 to 60 mm thick, more preferably 3 to 20 mm thick and preferably has a basis weight of about 5 to 300 glm2, more preferably about 5 to 100 g/m2 and most preferably 10 to 30 glm2.
Thermal bonding may be carried out by any means which can achieve adequate bonding of the staple bonding fibers to provide adequate structural $ability. Such means include, but are not limited to, ~,c,..v, : ' hot air ovens, microwave, or infrared energy sources.
The means of forming the layered batt is not critical. The layers may be o formed by cross-lapping, layering multiple doffs, by ganging web formers or any other layering technique. The batts of the invention may contain up to about 100layers, but generally contains about 5 to 30 layers and generally the effect can be seen with as few as two layers.
Preferably, the layered batt is post-treated to stabilize the layered structure.5 This can be done by heating the surface of the batt, such as by the use of co.,~ ' hot air ovens, microwave, or infrared energy sources to bond the perimeters of the layers on the periphery of the batt. This is shown in FIG. 2 where a batt 20 is seen in cross-section with layers 21 remaining individualized in the central portion of batt 20 and bemg bonded at the periphery 22.
~o In the Examples which follow, the following test methods were used.
Thickness Thickness of each batt was determined by applying a 13.8 Pa (0.002 psi) force on the face utilizing a Low Pressure Thickness Gauge Model No. CS 1946 available from Custom Scientific Il.~,LI u---~ Inc.

W09~ 28 21 8878l r~.,u~ 4 Densitv The volume of a sample of each batt was determined by fixing two planar sample dimensions and measuring the thickness as described above. The density J was calculated by dividing the mass of each sample by the volume.
Thennal ~
Thermal resistance of the batts was determined according to ASTM-D-1518-85 to determine the combined heat loss due to convection, conduction and radiation The hand of each batt was evaluated and ranked on a scale of ranging, from poor, fair, good, to excellent.
The following examples further illustrate this invention, but the particular materials, and amounts thereof in these examples, as well as other conditions and details should not be construed to unduly limit this invention. In the examples, all parts and pc. ~ .b... are by weight unless otherwise specified.
20 Examvles ]-6 In Example 1, staple fill fibers (75 weight percent Trevira~M Type 121 polyethylene t~" . ' ' ' , 1.2 denier, 3.8 cm long, available from Hoechst Celanese Corp.) and bonding fibers (25 weight percent core/sheath fiber preparedaccording to U.S Patent No. 4,950,541 and U.S. Patent No. 5,256,050, having a 25 core of polyethylene terephthate surrounded by a sheath of an adhesive polymer of linear low density p~ L~ graft copolymer, 2.2 denier, 2.5 cm long) were opened and mixed using a CromtexTM opener, available from Hergeth . . Jl 1ll, Inc. The fibers were conveyed to a carding machine that utilized a single doffing roll and a single condensing roll such that the card provided a web WO 95/32328 2 1 8 8 7 8 l F~~ S ~ --having one side on which the fiber are oriented primarily in the machine direction to provide a ' '1~ smooth surface while on the other surface the fibers are oriented in a more vertical direction to provide a loose fibrous character. The web was then passed through an air circulating oven at 218C at a rate of 1.68 meters :~
5 per minute to achieve a stabilized web. The web was then cross-lapped ~,UIIV. ''~ to a 12-layer batt.
In Example 2, a batt was prepared as in Example I except the fiber content was staple fill fibers (55 weight percent Trevira~ Type 121 PUIJ~ h~IC
l,alGL~, 1.2 denier, 3.8 cm long, available from Hoechst Celanese Corp.) o and staple bonding fibers (45 weight percent of the core/sheath fiber used in Example 1).
In Example 3, a batt was prepared as in Example I except the fiber contents staple fill fibers (25 weight percent Trevira~M Type 121 p~ ,il.J!~
~ele~Jl.illalGle, 1.2 denier, 3.8 cm long, available from Hoechst Celanese Corp.) 5 and staple bonding fibers (75 weight percent of the core/sheath fiber used in Example 1) and the web was 11 u ,,lG~,cd to form a 12 layer batt.
In Example 4, a batt was prepared as in Example I except the fiber content as staple fill fibers (55 weight percent TreviralM Type 121 pGl~ ,.le ~ele~ lllGlalè, 1.2 denier, 3.8 cm long, available from Hoechst Celanese Corp.) 20 and staple bonding fibers (45 weight percent of the core/sheath fiber used in Example 1) and the web was .,IU~IG~ J to form a S layer batt.
In Example 5, a batt was prepared as in Example I except the fiber content as staple fill fibers (55 weight percent Trevira~U Type 121 ~ L~
e~ l.dlGl~, 1.2 denier, 3.8 cm long, available from Hoechst Celanese Corp.) ~5 and staple bonding fibers (45 weight percent of the core/sheath fiber used in Example 1) and the web was "l U~IG~ to form a 20 layer batt.

WO95132328 2188781 r~ .,..'sl94 Il In Example 6, a batt was prepared as in Example I except the fiber content as staple fill fibers (55 weight percent Fortrell'U Type 69460 pul~,.l,yL,.,~, Lt~ t~, 0.5 denier, 3.8 cm long, aYailable from Wellman Fiber Industries, J Florence, SC) and staple bonding fibers (45 weight percent of the core/sheath fiber used in Example 1).
In Example 7, a batt was prepared as in Example I except the fiber content was staple fill fibers (55 weight percent TreviraTM Type 121 ~GI~
l~lt, ' ' ' ', 0.85 denier, 3.8 cm long, available from Hoechst Celanese Corp.) and staple bonding fibers (45 weight percent of the core/sheath fiber used in o Example 1).
Samples were tested for basis weight, bulk density, thickness, thermal resistance, thermal weight efficiency and hand. The test results are set forth in Table I.
Tanle ~
` sample I 2 4 5 6 7 Il Fiber (o/0) 75 55 ' 55 55 55 55 onding Fiber 25 45 7 45 45 45 45 asis Weight (glmZ) 233 240 255 101 383 221 250 Thickness (cm) 10.6 9.5 9.8 3.7 ~4.4 8.2 14.9 sulk Density (k~m3) 2.2 2.5 2.6 2.7 2.7 2.X 1.7 Thermal Resistance (clo) 7.4 7.0 6.9 3.1 10.4 7.6 8.8 Ther~nal Weight E~iciency 31.8 29.2 23.6 30.3 27.2 30.4 35.2 (cloAcg/mZ) 15Hand Excel. Excel. Excel. Excel. Excel. Excel. Excel.
As can be seen from the data in Table 1, in Examples 1, 2 and 3 changing the amount of bonding fiber does not substantially affect the thickness, density or hand, but increasing the amount of the larger denier fill fiber decreases the thermal resistance and the thermal weight efficiency. At higher weights, thickness and 20 thermal resistance increased, the density remained ' "~, the same and W095B2328 2 1 8 8 7 8 1 ~l/U~ 011S4 thermal weight efficiency decreased. The auba~lLiGlly constant density d.,~llullaLl~L~,a that the bonding ofthe webs before layering holds the webs intact in the layers so that the weight of the layers does not compress the batt.
5 Examples 8-10 In Examples 8-10, batts were prepared as in Example I except using staple fill fibers (Trevira~ Type 121 pG~ ,L~ , L~ ' ', 1.2 denier, 3.8 cm long, available from Hoechst Celanese Corp.) and staple bonding fibers (the core/sheath fiber used in Example 1) in the amounts shown in Table Il with each batt formed lo by wuaall ~)y;.l~; 12 web layers and subsequent to wuaalG~ g the batt was surface bonded with infrared irradiation at 163C for 36 minutes. The batts were tested as in Examples 1-7. The results are reported in Table II.
Ta le II
:`xampl~ 9 ll Fiber /O) 55 onding F er (/0) 45 asis weignt ( lm2) ? l 8 ' hickness (cm ulk Density (~g/m3) hermal Resis ance (clo) b. . ' Ahemmal Weig lt Efficiency : . : .5 ? ~.3 (clolkg/m2) Hand Excellent Excellent Excellent As can be seen from the data in Table Il, surface bonding of the batts did also produced batts having excellent thermal resistance and thermal weight efficiency, although varying the amounts of the finer denier fill fibers did notappreciab]y affect these properties.
20 Comparative Examples Cl-C6 In Comparative Example Cl, a batt was prepared as in Example 2 except the web was not bonded prior to cross lapping. In Comparative Examples C2-C6, WO95/32328 2 ~ 88 78 1 ~ C ,~5~

various CO..I.l.~,., ' "~, available thermal insulating materials were evaluated using the test methods used in Examples 1-6. The materials were as follows: Goose Down 600 available from Company Store, Lacrosse, W1 (Comparative Example C2); Primaloff~i, available from Aibany Intentional Corp., Aibany, NY
5 (Comparative Example C3); Comforel~i, available from DuPont Co., Wilmington, DE (Comparative Example C4); Kod-O-FilThi, available from Eastman Chemica' Co., San Mateo, CA (Comparative Example C5); and ThermoloftTbi, available from DuPont, Inc. (Comparative Example C6). Test results are set forth im Table rlI.

Table lI
xampl Cl C2 C3 C4 C5 C6 Il Fiber ~o~0) 55 onding F er (%~ 45 asis Weig~il (g/mZ) 5 3~ 3 ' 7 4 2 hickness (cm) . . 3. -: -ulk Dcnsity ~kg/m3~ . . . 7.
hermal Resistance .. .~ 5.. ... ... ~.-(clo) Thermal Weight 22.2 31.1 17.3 19.8 15.S 13.4 Efficiency (clo/kg/mZ) Drape Hand Good Excellent Good Good Poor Fair As can be seen from the data in Table III, the unbonded batt of Comparative Example Cl had lower thermal resistance and thermal weight efficiency and poorer hand than the similar batt of Example 2. The down sample of 15 Comparative Example C2, had excellent thermal resistance, thermal weight efficiency and hand although it would be expected to exhibit an unpleasant odor when wet typical of down. Comparative Examples C3-C6 exhibited poorer thermal weight efficiency and hand than the down sample or the batts of the invention.

Claims

What is claimed is:

1. A nonwoven thermal insulating batt comprising multiple layers of webs, each web comprising a blend of 5 to 100 weight percent bonding staple fibers and 0 to 95 weight percent staple fill fibers, the bonding fibers bonded to other bonding fibers and fill fibers at the points of contact within each layer to enhance the structural stability of the layers of the batt, said layered batt being further bonded at the perimeter of the layers on the periphery of the batt and the interior portions of the layers not being bonded to adjacent layers.

2. The nonwoven thermal insulating batt of claim 1 wherein said batt contains staple fill fibers of two or more deniers.

3. The nonwoven thermal insulating batt of claim 1 wherein said batt contains staple bonding fibers of two or more deniers.

4. The nonwoven thermal insulating batt of claim 1 wherein said batt has a thermal weight efficiency of at least 20 clo/kg/m2.

5. The nonwoven thermal insulating batt of claim 1 wherein said batt has a bulk density of less than about 0.1 g/cm2.

6. The nonwoven thermal insulating batt of claim 1 wherein said batt has a thickness in the range of about 0.5 to 50 cm.

7. A method of making a thermal insulating nonwoven multilayer batt comprising the steps of:
(a) forming a web of bonding staple fibers and staple fill fibers;

(b) subjecting said web to sufficient heat to cause bonding of the bonding staple fibers to other bonding staple fibers and staple fill fibers at points of contact to stabilize the web;

(c) forming a batt of multiple layers of said webs; and (d) bonding the layers at the periphery of the batt such that interior portions are not bonded to adjacent layers.

8. The method of claim 7 wherein the web is formed by carding, garnetting or air laying.

9. The method of claim 7 wherein the web is formed by carding.

10. The method of claim 7 wherein the card is equipped with a single doffing roll and a condensing roll to provide each of the layers with a substantially smooth side and a loose fibrous side.

11. The method of claim 7 wherein said bonding is achieved through use of convection oven, microwave or infrared energy sources or a combination thereof.

12. The method of claim 7 wherein the layering is achieved by cross-lapping, layering of multiple doffs or by ganging of the web forming equipment.

13. The method of claim 7 wherein the layering is achieved by cross-lapping.

14. The method of claim 7 wherein the batt comprises 10 to 80 weight percent staple bonding fiber and 20 to 90 weight percent staple fill fibers.

15. The method of claim 7 wherein step d) is carried out by heating the surface of the batt to bond the outer edges of the layers of the batt.

16. The method of claim 15 wherein said bonding is achieved through use of convection over, microwave or infrared energy sources or a combination thereof.